The present invention provides a hypoglycemic composition and preparation method thereof, wherein the hypoglycemic composition comprises 1-99 parts by weight of anise oil and 1-99 parts by weight of onion oil. Compared with the prior art, the anise oil in the hypoglycemic composition of the present invention can inhibit aldose reductase and α-glucosidase. The active ingredients of onion oil are sulfonylurea butyric acid and volatile substances containing sulfur including alliin, allylpropyl disulfide, S-allylcysteine sulfoxide (SACS) and so on, which prevent insulin from being destroyed by oxidation-reduction equilibrium. Anise oil and onion oil act synergistically to facilitate the hypoglycemic effect moreover, anise oil and onion oil can be both used as medicine and food, and have no side effect.
